1. Field of the Invention
The present invention relates to a control for a vehicular powertrain comprising a fuel-controlled engine and a multiple-ratio drivetrain, including a multiple-speed mechanical transmission and a single- or multiple-speed drive axle assembly. In particular, the present invention relates to a powertrain control wherein the maximum output torque of the engine is limited as a function of the degree of engagement of monitored jaw clutches.
2. Description of the Prior Art
Vehicular drivetrains including multiple-speed mechanical transmissions, usually compound transmissions, or simple transmissions coupled with multiple-speed axles, having 7, 9, 10, 13, 16, 18 or more forward speed ratios, are well known in the prior art, especially for heavy-duty vehicles, as may be seen by reference to U.S. Pat. Nos. 5,370,013; 5,527,237 and 4,754,665, the disclosures of which are incorporated herein by reference. Both synchronized and non-synchronized jaw clutches are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,546,823; 5,588,516 and 5,642,643, the disclosures of which are incorporated herein by reference.
Control systems and methods for calculating engine output torque (also called "flywheel torque") are known in the prior art, as may be seen by reference to U.S. Pat. No. 5,509,867, the disclosure of which is incorporated herein by reference.
Automated and manual transmission systems wherein engine output torque is controlled and/or limited as a function of engaged gear ratio and/or vehicle speed are known in the prior art, as may be seen by reference to U.S. Pat. Nos. 5,477,827; 5,797,110; 5,457,633; 4,889,014; 5,738,606; 5,679,096 and 5,876,302, the disclosures of which are incorporated herein by reference. As is known, modern vehicular powertrains usually include electronically controlled engines, which may be controlled as to engine speed and/or engine torque. By way of example, according to the SAE J-1939 data link protocol, commands may be issued to the engine for fueling of the engine in accordance with (a) driver's fuel demand, (b) a requested engine speed, (c) a requested engine torque and/or (d) a requested maximum engine torque and/or engine speed.
While the prior art systems are effective in protecting the vehicle driveline from undue wear and/or damage resulting from greater-than-desirable torque being applied for a particular engaged ratio and/or driveline configuration, the systems do not prevent possible undue wear and/or damage resulting from partial jaw clutch engagement.